CHARACTERS OF SIMIIDAK
existing genera, Cebus, Mycetes, and Callitlirix, now living in South
America, are also known in a fossil state. The extinct genus
Homunculus is known from the Tertiary strata of Patagonia, and
an apparently allied form is Antliropops. These creatures, how-
ever, are at present far from exhaustively known.
Fam. 2. Simiidae.—The Anthropoid, or Man-like Apes/
may be separated from the lower Apes as a group, Simiae,
or perhaps better, on account of the after all slender points of
difference, a family Simiidae, which has the following distinctive
Though arboreal creatures for the most part, these Apes, when
they come to the ground, progress in at least a semi-erect fashion.
Moreover, when they, as is usually the case, put their hands
upon the ground to aid in walking, they do not rest as do the
lower Apes upon the flat of the hand, but upon the back of the
fingers. ISTone of the Anthropoids has a tail, or cheek pouches.
Ischial callosities are only seen in the Gibbons. There is
commonly a laryngeal pouch, which is of large size, and aids in
the production of the generally loud voice of these creatures.
The hair is rather more scanty than in the Cercopithecidae, which
is an approach to Man. The placenta differs in detail from that of
the lower Apes, and is exactly like that of Man. These Apes show
as farther differences from the underlying Cercopithecidae, the
greater length of the arms as compared with the legs, and the
presence of a vermiform appendix to the caecum. In the latter
but not the former character they agree with Man, whom we
shall place in a separate family, Hominidae. The Anthropoid Apes
are entirely Old World and intratropical in range at the present
The Gibbons, genus Hylobates, stand quite at the base of the
series of existing Anthropoid Apes. They are the smallest and
the most purely tree-frequenting of all the members of that
group. Connected with this habit is the structural peculiarity
that their arms are proportionately longer than in the other
Anthropoids. The affinity of the Gibbons to the Catarrhines is
proved by the presence of distinct but smail ischial callosities.
Tfce arms are so long that when walking upright the hands
reach the ground. The hallux is well developed. The ribs are
pairs. In the skull the chief noteworthy character as
1 See the books quoted on p. 576 (footnote).